1. Technical Field
The present invention relates to a fluid transportation system and a method of setting a fluid ejection amount in the fluid transportation system. For details, the present invention relates to a fluid transportation system equipped with a miniature fluid transportation device, an ejection data processing device, and a communication device, and to a fluid ejection amount setting method for accurately setting an amount of fluid ejection.
2. Related Art
In recent years, application of a miniature pump, which is used for continuously administering a small amount of medicinal liquid to a patient in a form of a slow current, to treatment has been studied.
For example, as first related art, there is cited a miniature peristaltic pump device suitable for attachment to a human body for slowly and continuously injecting it with an aqueous medicinal liquid in which a rotor of the pump is attached to a shaft, the rotor being provided with a plurality of rollers disposed to be evenly distributed on the periphery of the shaft, the rollers perform rotational movement while rotating along a flexible tube to press the tube against a backing surrounding the tube in a circular range with a predetermined length, thus performing suction and ejection of a fluid such as a medicinal liquid.
There is known such a miniature peristaltic pump device provided with a stepping motor as a power supply driven at a rotational speed set previously by a block IC having a control circuit, thus achieving a desired amount of ejection (Japanese Patent No. 3177742).
Further, as second related art, there is known a peristaltic pump device provided with a miniature peristaltic pump, an input switch for setting the fluid ejection amount of the miniature peristaltic pump to a plurality of levels and setting the fluid ejection amount by selecting from the plurality of setting levels, and a display section disposed on a housing (specification of U.S. Pat. No. 3,737,251).
In the invention according to the first related art described above, although the ejection amount of the medicinal liquid and so on can be set or changed in accordance with the number of frequency divider stages for receiving a signal supplied from a time base, a reduction ratio of a gear mechanism, or a type of a motor used therefor, it is required to be manufactured with the setting condition determined previously. However, the ejection condition once determined is unchangeable, and there arises a problem that it is difficult to set the fluid ejection amount while arbitrarily changing the form of usage or the condition of administering the medicinal liquid.
Further, in the invention according to the second related art, although the switch for adjusting the ejection amount of the fluid, the display section, and the peristaltic pump are disposed on the housing so as to allow the adjustment of the ejection amount, downsizing is difficult with such a configuration in which the miniature peristaltic pump, the switch, and the display section are mounted on the housing, and consequently, it can hardly be mounted inside a body of a small animal for the purpose of developing a new drug and so on.
Further, the inventions according to the first and second related art described above relate to a peristaltic pump for ejecting a liquid by squeezing a tube, and consequently, an ejection amount of the liquid is proportional to the square (the cross-sectional area) of the diameter of a liquid flow section of the tube. Further, there might be caused a variation in diameter of the tube having flexibility in the manufacturing process thereof. In particular, it is well known that there is a variation among production lots.
Such a variation in diameter of the tube causes a variation in ejection amount of the liquid, and in particular in the case of the application to administration of a medicinal liquid, the variation in tube diameter is a substantive issue because a small amount of ejection is continuously performed and accurate ejection amount control is required. However, in the first and second related art described above, there is a problem that the accurate adjustment of the ejection amount in consideration of the variation in tube diameter can hardly be performed.
Further, it is conceivable that it does not cope with a variation in remaining power or voltage of a battery as a power supply, improper driving of the pump, shortage of drive period, and so on, and consequently, it is inferred that a significant problem unable to be left unsolved arises in the case of administration of a medicinal liquid.